A collection of online resources all Neptune 4 owners should be familiar with.
Elegoo includes most all the basic tools you need to assemble and maintain the printer.
Consider purchasing the following:
While the coverage of assembly and set up is authoritative, its methods for bed leveling and setting the nozzle height adjustment (gcode z offset) should be avoided, and Klipper's native screws_tilt_calculate used for bed leveling instead.
The canonical 3D print troubleshooting page (which is pinned on the r/fixmyprint Reddit) is located at https://www.simplify3d.com/resources/print-quality-troubleshooting/ Consult and try its recommendations before asking questions about print quality issues you may experiencing.
Creality has a "The 10 Most Common 3D Printing Problems and How to Fix Them" page.
The Klipper docs, including the Klipper gcodes which are different from Marlin are on your printer and also online at https://www.klipper3d.org/
Orca Slicer web site: https://www.orcaslicer.com/
Documentation: https://github.com/SoftFever/OrcaSlicer
Wiki: https://github.com/SoftFever/OrcaSlicer/wiki
Orca Slicer getting started guide - https://youtu.be/cquTCpz1V74
Also watch: https://youtu.be/MqQak88YafU?si=0YMAO-EVmKvTNIMc
Mastering Your Prints: The Comprehensive OrcaSlicer Calibration Guide
A well regarded tuning guide, geared to Voron based Klipper printers yet still relevant, https://ellis3dp.com/Print-Tuning-Guide/
WildRose Builds' tuning guides are generally good, yet ignore for bed leveling and setting the gcode z offset as there are better alternatives.
https://www.obico.io/blog/orcaslicer-3d-printer-calibration/
Bambu Labs, while designed with their printers in mind, have some excellent references and troubleshooting how-tos that apply in most cases to all printers, and focuses around Bambu Studio as the slicer, from which Orca is based so lots applies. In case related directly to the printer most everything can be interpolated to the N4 series accordingly.
https://wiki.bambulab.com/en/knowledge-sharing/common-print-quality-problem https://wiki.bambulab.com/en/knowledge-sharing/troubleshooting-printing-issues https://wiki.bambulab.com/en/filament-acc/filament/slice-param
See Orca for built in calibration models for:
A faster, less subjective flow ratio test that's more functionality focused and uses way less filament can be found at https://www.printables.com/model/1113488-flexi-flow-calibration-tool-v4-by-ck3d
Grabby the Claw - a quick calibration test for 3D printed action figures! (“not a comprehensive guide to tuning your printer in general.” Also its troubleshooting tips are geared toward non-klipper parlance, so apply some translation to get the gist, it's just mostly a good model, yet not for PLA.)
A WIP from Rob Trame's “R6E Projects Blog” with a great breakdown of the Neptune 4 hardware